Illuminated sign or signal



ILLUMINATED slGN oR SIGNAL Filed Sept. 8. 1923 2 Sheets-Sheet l i LLAALA P. H. SCHULZ ET AL" ILLUMINATED SIGN on SIGNAL July l2 1927.

Filed Sept.v8. 1926 2 Sheets-Sheet 2 Patented July 12, 1927. A

UNITED STATES PAUL H. SCHULZ AND JESSEN, F MILWAUKEE, WISCONSIN,ASSIGNOBS T0 1,635,863 PATENT OFFICE.-

TRAIFIC CONTROL, INC., 0I' IILWAUKEE, WISCONSIN, A CORPORATION 0l' WIS-fcousin.

ILLUm'ATED SIGN 0B SIGNAL.

Our invention relates to appliances in which transparent portions areilluminated by light from behind the saine, and in some of its generalobjects aims to Vprovide means for increasing .or intensifying .theillumination of the sign front portions which are to contrast with anopaque or less brightly illuminated field or ackground so as to -presentthe desired indicia or legend.

In one aspect, .our invention relates to signs, signals or the like andaims to provide means for increasing the attention-attracting qualityand the legibility of the .sign or signal when viewed from a directionl5 approximately perpendicular to the plane of the sign or signal. Moreparticularly, our

invention relates to an illuminated signal, sign or the like, in whichtransparent portions are illuminated by a source of light behind thesame, and aims to provide a lens construction interposed betweenthelight source and the indicia-carryin sign front, which lens constructionis so ormed as to redirect a. considerable portion of the emitted lightinto a beam whose rays are approximately parallel and to cause this beamto fall upon the rear side of the transarent indicia portions of thesignal or sign in a direction approximately perpendicular to the planethereof.

In another aspect, our invention provides for a sign, signal, or thelike, transparent portions of which are illuminated by a source behindthe same, and further provides a reflector located behind the lightsource and so constructed as to redirect avconsiderable .portion ofthe.ernitted light into a beam whose rays are approximately arallel andto cause this beam to fall upon t e rear side 4o of the transparentportions of the signal or sign in a direction approximatelyperpendicular to the plane thereof.

In a further important aspect, our invention relates to signs, signalsor the like, and

aims to provide means for utilizing a much larger portion of the lightthan has hitherto been customary, for lighting the legend or otherinsignia thereof. More particularly, our invention relates to anilluminated sig- 5o ual, sign or the like in which transparent portionsof a front of glass or of some other refracting medium are illuminatedby a source of light behind the same, and aims to provide a frontconstruction for this purpose which will cause such transparent por-'light which falls upon considerably tions to be effectively illuminatedbly the arger portions of the rear face of the said front. Our inventionalso aims to provide means for directing light toward the said rear facep ortions in such a manner as to have the l1 ht effectively utilized bythe construction o the front above referred to. For this latter purposeour invention aims to provide means (consisting either of reflectorsalone o r of reflectors and refractors in suitable combination) forparallelizing the imiter part of the rays from the source of lig t intoa general direction at right angles to the lamp front.

More particular-l our invention rovides a reflector arrange forredirectin t e rearwardly emitted light forwardly su ntially through thesource of light, and provides a glass refracting member havin prismaticportions arranged for parallelizing the resulting forwardly radiatedlight, this ref racting member having its` prismatic formations shapedin denite relation to the source of light, or to the several sources oflight when more than one is employed. Still further and also moredetailed objects will appear from the following specification and fromthe accompanying drawin in which Fig. 1 is a perspective view o a stopsignal or tratlic control signal embodying our invention.

Fig. 2 is an enlarged and horizontal transverse section through the sameembodiment.

Fi 3 is a correspondingly enlarged longitu inal and vertical sectiontaken through one of the sources of light, or along the line 3 3 of Fig.2.

Fig. 4 is a fragmentary front elevation of the inner light-refractingmember of Fig. 2, showing the arrangement of the prismatic ribbing onthe same as employed with two lamps.

Fig. 5 is a corresponding front elevation of a similar light refractingmember as emplo ed with a single source of li ht.

l* ig. 6 is a corresponding elevation, drawn on a smaller scale, of alight refracting memperi designed for use with four sources of ig it.

Fig. 7 is an enlarged front elevation of the glass front of the sign orsignal of Fi 1,

with dotted lines showing the correspon 'ng contour of the letterformations at their rear.

Fig. 8 is a fragmentary and enlarged section through such a sign orsignal front, showing the double refraction of the rays of light whenpassing through the saine.

Fig. 9 is a similar section through a ortion of a glass sign front of adifferent orm from Fig. 8, namely one having a flat forward face. p

Fig. 10 is a similar section through a glass front in which the lensformations are double convexed. t

Fig. 11 is an enlargement of a portion of a section of Fig. 8 showingthe angle of refractive condensation throu h the lass.

Fi 12 is a central and ongitu 'nal section rough a signal lamp embodyingour invention and ein loying a reiector designed for paralle izing therays of l1 ht without the use of a light-refracting mein r between itand the sign front.

In its immediate commercial aspects, our invention is particularlysuited for use with traic control signals as employed at streetintersections, and with lamps employed on the rear of vehicles forindicating when the vehicle is to stop or otherwise slacken its speed.We are therefore illustratin land describing our invention inembodiments particularly suited to such purposes, although we do notwish to be limited to any particular use of the novel lamp, sign orsignalconstruction here disclosed.

In the'embodiment of Figs. l to 4 inclusive, we are showing a singlelamp having two incandescent lamps l and 2 disposed within a casing 3.This casin desirably is formed of a pair of substantia ly spheroidalportions adjoined to each other between the lamps and aording a singleand rectangular mouth or frontal opening, the spheroidal back portionsbeing respectively7 concentric with the filament centers of the amps.Disposed across the said mouth is a glass .front 4 having all except theletter or insignia portions 5 rendered opaque by any suitable means,these latter portions being of a clear and transparent glass which mayor may not be colored.

If these letters simply comprised correspondingly outlined transparentportions on a fiat glass plate, in accordance with the customaryractice, the light issuing throu h each wouldp be proportioned directlyto t e area thereof, and owing to the relatively large size of theopaque or substantially opa ue background, a large roportion of the ightwould be wasted. o reduce this waste and to increase the intensity ofillumination of the sign or signal letters, we form the glass so thateach letter portion comprises a light-concentrating lens having at therear face of the glass late a contour corres onding tothe forwar contourof the -same etter but considerably larger in diuniform concave sectiontransversely of the medial line of each outlined portion of the letter,and make the rear face of the letters correspondingly convexed, thedifference in width being determined by the refractive index of the kindof glass employed. For example, if the forward face of a letter is tohave the width A in Fig. 11, the corresponding width B of the sameletter portion at the rear of the glass front is determined by the angleC which is computed from the index of refraction of the particular glassused, this being substantially the limiting angle at which refractionwill occur without surface reflection. So also the angle D between :iperpendicular to the eneral plane of the front face and the ra ius ofthe forwardly concaved face E of the letter is likewise computed fromthe index of refraction of the particular glass used, according to wellknown optical principles which need not here be discussed. The center Fas thus found opposite the middle of the face E is also desirabl thecenter of curvature of the rear face of the corresponding letterportion.

vWith. the parts thus computed for affording the maximum availableconcentration of rays of light striking the rear of the glass front indirections perpendicular to the eneral plane of the latter, it will beevi ent from Fig. 1l and from the dotted outlines 6 in Fig. 7 that thelight-receiving rear face of each letter has an area much greater thanthe forward face of the letter. Consequently, we aie able to utilize notonly the light striking the glass front from directly behind the forwardface of the letters, but also a relatively larger amount of li htstriking portions of the glass front which are directly behind opaqueportions of this front.

To secure the maximum effectiveness from a glass sign or signal front asthus constructed, we also employ means for redirecting rays from thesource or sources of light so that these rays will impinge on-the rearof the lass front along lines substantially perpen iculai` to the faceof the latter or parallel to the medial plane K of the lens formation ofFig. 11. While a. substantially paraboloidal reflector behind a lampwould effect such a parallelizing in so far as the rearward rays oflight from the lamp are concerned, such a refiector has no effect on therays of light issuing direct from the lamp towards the glass front. Toredirect this latter class of rays also, we desirably employ refiectorswhich are substantially spheroidal and concentric with the sources oflight und also interpose between the lamp or lamps and the glass front 4a light-refracting member 6 arranged for affording the desired parallelredirection of such rays. This refracting member is desirably in theform of a glass plate having a iiat rear surresuena face and havin itsforward surface provided with ribs affording the desired rismaticeffect. Where the source of lig t is an incandescent lam having areltively small filament the ri bin r on the lignt refracting mem er ispre erably concentric about the per endicular 8 as drawn from the centerof tlie source of light to the lass front. Where two lamps are em loyebehind a single glass front, as in t ecase of Fig. 2, the ribbing whichis concentric with each of the two axes 8 and 8^ is carried only to aline 9 disposed midway between the said two axis and at right angles toa line 10 connecting the two axes.

With the filament center of each lamp at the center of one of thespheroidal reflector portions, the rays of light issuing rearwardly fromeach lamp towards the adjacent reflector are directed right backsubstantially through the source of light, so that by far the largerportion of the light issues towards the refracting member in raysradiating from the sources of light. Consequently, by employing annularprisms which are also concentric with the source or sources of light, wecan definitely redirect the greater portion of the emitted light intoparallel rays perpendicular to the lamp front, the prismatic formationsbeing suitably varied 1n section according to their distances from theadjacent source of light so as to produce the desired refraction inaccordance with well known optical principles. Then the parallel raysthus directedagainst the rear lens faces of the letters or other indiciaare effectively concentrated and emitted in parallel rays after themanner shown in Fig. 8.

To maintain the refracting member in proper position with respect to thelamps, we deslrably equip the casing with suitable shoulder formations,such as the annular shoulder 10 shown in Figs. 2 and 3, which shoulderis afforded by an outwardly directed fiange connecting the reflector orback portion of the casing 3 with a forwardly directed mouth portion 11.Then we also desirably provide one of the members 4 and 6 with a spacerfiange 12 adjacent to its periphery and bearing against the othermember, so as to maintain the refracting ribs on the member 6 suitablyspaced from the rear of the lens-letter formations. Thus arranged, itwill be obvious from Figs. 2 and 3 that these glass parts can easilybeassembled and jointly secured in proper position by attaching a collar13 to the mouth of the casing in the usual manner.

However, while we have heretofore described our invention in anembodiment employing two sources of light and having integral letter orinsignia portions formed with concave fronts and convex rear faces, wedo not wish to be limited to these or other details of the constructionand arrangement\ thus disclosed. Obviously, many changes might be madein the construction and arrangement vwithout departing either from thespirit of our invention or from the appended claims.

For example, if only a single lamp was to be used behind a glass sign orsignal front of the general pro ortions of that employed 1n Flg. 1, theauxi iary refracting plate may desirably have all of its ribsconcentrically disposed about a single axis after the manner of Fig. 5.On the other hand, if the sign or signal is relatively long and isilluminated by four lamps, the prismatic formations would desirably becentered about: four different axes respectively in alinement with theluminescent centers of the lamps, after the manner illustrated in Fig.6. So also, the sign front need not necessarily'have convex front facesfor the insignia portions. For example, the entire forward face of theglass front plate 4 might be fiat so as to afford only a lano-convexlens formation, in which case t e rays of light issuing from each letterwould intersect at some distance from the said front face after themanner of Fig. 9. Or, these insignia fronts might be convexed so as toafford a double convex lens formation, in which case the intersection ofthe issuing rays of light would be closer to the front face ofthe glassand these rays would be more widely disbursed. vThat is to say, thepreliminary parallelizing of such a large proportion of the rays ofllght makes our appliance so much more efficient that the constructionof the insignia portions may be varied eatly while still affording amuch more e ective signal indication than is obl tained with the signalappliances now in common use. Indeed, this increase in effectivenesswill even be obtained with glass fronts having no lrefracting formationsfor the letters or other indicia.

On the other hand, our lens-letter-carrying glass front would also bemuch more effective than the ordinary sign fronts now in use if employedwithout an intervenin refracting member, hence this important eature ofour invention may be employed by itself. For example, by using aparaboloidal reflector after the manner shown in Fig. 12, this willparallelze the rays of light reaching it direct from the lamp and thesubsequent concentrating lens effect will afford a greatly intensifiedillumination of the signal or sign forming letters or other indicia.Being thus able to secure decided advanta es by using certain featuresof our many-si ed invention independently of each other whenever thismay seem desirable, we do not wish to be limited to the joint employmentof spheroidal reflectors, concentrically ribbed refracting members andlens-forming insignia. Neither do we wish to be limited to the variousdetails of construction, shape or arlllr rangement here disclosed, itbeing obviousv that many changes might be made without departing eitherfrom the s irit of our invention or from the append claims.

We claim as our invention 1. A front for an illuminated sign comprising.a lass member having translucent ortions t ereof shaped to correspond inrontal contour to desired sign letters, each of the said portions havingva uniform transstantially concentric with the said rear face.

3. In an illuminated sign or the like, a

source of light, a glass front, means for di-` recting light from thesaid source to the glass front 1n rays per endicular to the general laneof the sald ont, the glass front havlng inte ral formations conformingin contour to t e insignia to be displayed, each of the said formationsbeing formed for con'- densing li ht while passing through `it andemitting t ev said lig t in rays also perpendicular to the said generalplane.

4. A glass front for an illuminated sign, signal or the like, having asintegral portions thereof translucent condensing lens formationsconforming in contour to the insignia to be displayed, each of the saidlens forma tions having a uniform concavo-convex transverse section withthe convex edge of the section disposed inwardly of the sign or thelike.

5. A sign, signal or the like comprisin a source of light, alightrefracting mem r consisting of a glass plate disposed in front of thesource of light and having its forward face prismatically. ribbed torefract Losanna the light rays passing through4 the glass plate so thatthe said rays will issue substantlally at right angles to the glassplate, and a f rontal member having transparent glass lnsignia portionsformed for converging the rays of light refracted'upon the same by thesald lass member.

6. n illuminated appliance as per claim 5, in which the frontal memberhas its insignia portions spaced from the glass refracting member andpresenting convex rear faces toward the latter.

X7. An illuminated appliance as per claim 5,"in which the frontal memberhas its insignia port-ions spaced from the glass refracting member andpresenting convex rear faces. toward the latter, and in which the saidinsignia portions have forward faces narrower than their said rearfaces,v

p 8. An illuminated appliance as per claim 5, in which the frontalmember has its insignia portions spaced from the glass refracting memberand presenting convex rear faces toward the latter, and in which thesaid insignia portions have forward faces narrower than their saidrear'facesoand substantially concentric with the latter.,

9. In a sign, signal or the like, the combination of a source of light,a front member including translucent glass insi ia portions, and a lightrefracting member interposed between t e front member and the source oflight, the light-refracting member beingY rovided with prisms forredirecting rays rom the source of light against the rear faces of theinsignia in lines perpendicular. to the general plane of the frontmember, and the insignia being formed for concentrating the rays oflight directed to the same along the said lines.

Signed at Milwaukee, Wisconsin, March 27th, 1923. y

PAUL H. soHULz CHRISTIAN JEssEN.

